Introduction
 We have developed 3 types of in situ automatic time-series benthic samplers and have used them successfully in shallow coastal environments for the past 5 years to examine the effects of tidal state, diurnal changes in light, and current velocity on larval abundances in the water and the recruitment of benthic species onto deployed substrates or sediment. The first of these samplers is a time-series sampler (ELVIS - see Whitlatch and Osman 1998. Limnology and Oceanography 43: 516) that measures the recruitment of sessile benthic invertebrates onto hard substrates. This device exposes 4 sets of 4 replicate samplers with each set taken at a different environmental condition. Sampling times can be pre-programmed (e.g. using predicted tidal or diurnal cycles) or controlled by one or more external sensors (e.g. we have  used current meters to control sampling relative to current velocity and direction). The second device is a plankton pump sampler (LISA) that measures the larval densities of benthic species but can also be modified to measure abundances of smaller phyto- and zoo-plankton. Presently, these devices are configured to take and preserve 4 sets of plankton samples and can be programmed to respond to sensors in a similar manner as the ELVIS device. The third device (JESSE) is designed to measure changes in recruitment into sedimentary environments and resultant community composition. Each contains 4 chambers filled with azooic sediment and is buried in natural sediments such that the chambers are flush with the sediment surface. As in the other devices, one or more monitored environmental conditions can be used to control the exposure schedule. In addition, these devices are currently being fitted with sets of probes that monitor oxygen and hydrogen sulfide within the sediment column of each chamber.
Quick links to information for:
Larval in situ sampling apparatus (LISA)
Electronic in situ larval settlement sampler (ELVIS)
Jacent electronic soft settlement ELVIS (JESSE)
Larval in situ sampling apparatus (LISA) aka automated plankton pump
 Features: 4 sampling cups
Pumping rate of 15 liters per minute
Autonomous or slave mode
Uses: Assessing plankton abundance in water column.
This is rocket science! Plankton pump rocket, that is.
Features: Modified plankton pump sampler that can
be placed on hard or soft substrates.
Uses: Examination of larval release from benthic invertebrates.
Studies of benthos diurnal migration from the seafloor.
Solar power is a recent addition that allows us to run a plankton pump for longer periods of time.
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Electronic in situ larval settlement sampler (ELVIS)
Features: 16 circular, rotating PVC settlement panels that are exposed in groups of 4
Programmable for tidal or diel exposure
Uses: Assessing settlement and recruitment on hard substrata.
The figure below shows an example of how we use ELVIS to study recruitment of three species of ascidians in relationship to photoperiod. We preprogrammed the sampler to expose substrates at different periods of the day: ‘early morning’ (0600-0900), ‘mid-morning’ (0900-1200), ‘afternoon’ (1200-1500) and ‘evening’ (1500-0600). The sampler was deployed in the field for seven days. Results indicate higher recruitment before noon.
Using a several ELVIS machines simultaneously, it is possible to examine interactions of several physical factors influencing epifaunal recruitment dynamics. We deployed the units at a field site in which tidal flow varied from ~20 cm sec-1 at maximum flooding conditions to ~2-3 cm sec-1 during slack water periods for a 7 day period. One ELVIS was programmed to expose substrates at different stages of the tide, while another ELVIS was programmed to expose substrates at different periods of the day. The figure below indicates that ~80% of total recruitment of organisms at this site occurred before noon at slack water periods.
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Jacent Electronic Soft Sediment ELVIS (JESSE)
Features: 4 sampling cups
Uses: Assessing recruitment dynamics
of soft sediment invertebrates and
substrate selection of benthos.
Using the JESSE sampler, we are able to examine recruitment of infaunal organisms in relation to different environmental as well as sediment types. The graph below indicates strong differences in recruitment relative to different stages of the tide and that organisms only showed substrate selection at high, slack water conditions.
Recruitment dynamics in soft sediment systems is controlled by two, often independent, sources of colonists: larvae settling from the water column and post- settlement recruits which are laterally affected across the seabed. Using the JESSE units, we are able to partition the relative contributions of the to colonist pools and how they contribute to recruitment under different physical conditions. The graph shows that “settlers” (= larvae) are primarily settled during high slack water conditions, while post-settlers are recruiting during flooding conditions.
The photo below shows a typical array deployment we have been using in recent field experiments. An ADV current meter is used as the environmental sensor to cue the sampling regime of ELVIS and LISA units. A continuous real-time data stream from is sent to a data processing unit (COLONEL) which evaluates the nature of the tidal velocity and direction and through a pre-determined algorithm indexes the automated samplers. In this configuration, we can then examine larval availability and recruitment simultaneously and how these vary with tide state.
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